When it comes to modern muscle car news it’s been one-way traffic for the Chevrolet Camaro this week. First the Camaro ZL1 set a smoking hot time of 7:41.27 at the Nurburgring closely followed by Chevrolet announcing that the 2012 Camaro ZL1 convertible will be launching next month (read news). Now to finish the week in style, specialist American tuner Hennessey has revealed its latest special edition – 20th Anniversary Edition Camaro.

It’s not the Camaro’s 20th anniversary, but it is Hennessey’s 20th birthday so the tuner is going big with this celebratory Camaro. Officially named the HPE650 Camaro, this muscle car packs 655 horsepower achieved by fitting a TVS2300 supercharger. There’s also a new cam, replacement headers and intake and exhaust upgrades.

Subaru is celebrating 20 years of building low-mounted, boxer-powered, all-wheel-drive fun, with a new limited edition variant. The Subaru Impreza WRX STI 20th Anniversary edition doesn’t get too much in the way of modifications. The only major changes to the STI’s dynamics come from a new set of coilovers with retuned springs and shocks to offer a better ride, along with thicker front and rear anti-roll bars and a set of 18-inch rims to compliment the only available colour (white). Body mods are also kept to a minimum, with only a black lip spoiler and rear wing giving clues to the vehicles special status.

Naturally some unique badging is required, so in addition to leather Recaros with red stitching and a matching shift knob, a commemorative plaque on the center console and a new set of door sills let people know that the Impreza is one of the 300 limited edition examples.

Sales are limited to the Japanese domestic market with the Anniversary edition carrying a price tag of 4,126,500 yen ($81,200 NZ).